Schulman L H, Pelka H
Department of Developmental Biology and Cancer, Albert Einstein College of Medicine, Bronx, NY 10461.
Nucleic Acids Res. 1990 Jan 25;18(2):285-9. doi: 10.1093/nar/18.2.285.
Recent evidence indicates that the anticodon may often play a crucial role in selection of tRNAs by aminoacyl-tRNA synthetases. In order to quantitate the contribution of the anticodon to discrimination between cognate and noncognate tRNAs by E. coli threonyl-tRNA synthetase, derivatives of the E. coli elongator methionine tRNA (tRNA(mMet)) containing wild type and threonine anticodons have been synthesized in vitro and assayed for threonine acceptor activity. Substitution of the threonine anticodon GGU for the methionine anticodon CAU increased the threonine acceptor activity of tRNA(mMet) by four orders of magnitude while reducing methionine acceptor activity by an even greater amount. These results indicate that the anticodon is the major element which determines the identity of both threonine and methionine tRNAs.
最近的证据表明，反密码子在氨酰-tRNA合成酶选择tRNA的过程中可能常常发挥关键作用。为了定量分析反密码子对大肠杆菌苏氨酰-tRNA合成酶区分同源和非同源tRNA的贡献，已在体外合成了含有野生型和苏氨酸反密码子的大肠杆菌延伸甲硫氨酸tRNA（tRNA(mMet)）衍生物，并对其苏氨酸接受活性进行了测定。用苏氨酸反密码子GGU替换甲硫氨酸反密码子CAU，使tRNA(mMet)的苏氨酸接受活性提高了四个数量级，同时使甲硫氨酸接受活性降低得更多。这些结果表明，反密码子是决定苏氨酸和甲硫氨酸tRNA身份的主要因素。
